The present invention generally relates to a microwave device and more particularly, to a microwave device such as an electrical filter, a branching filter or the like employing coaxial resonators, for example, transverse electro-magnetic mode coaxial resonators (referred to as TEM coaxial resonators hereinbelow) which have improved designs especially advantageous from the viewpoint of manufacture.
Generally, microwave devices utilizing coaxial resonators have been widely used in electrical and electronic equipment operating, for example, in VHF and UHF ranges.
For the electrical filters as described above, there has been proposed, for example, in U.S. Pat. No. 4,151,494 assigned to the assignee of the present invention, an electrical filter employing coaxial TEM resonators mainly for the purpose of reducing the filter size, etc. in accord with the recent trend to miniaturization of electrical and electronic equipment. But the known electrical filter as described above still has some problems to be solved with respect to its performance, and with respect to the efficiency of its manufacture.
Similarly, other microwave devices conventionally proposed also have certain disadvantages particularly in the complicated structures thereof with consequent large size, and are not necessarily suitable for mass production.